Gas tight seal



NOVn 15, 1982. G BUECH'NER 1,888,070

c1118 TIGHT SEAL I 4Filed Sept. 5. 1928 Patented Nov. 15, 19632 y UNITEDST.ATES PATENT oFFlcE GUENTHEB BUECKHNEB, OF SCOTIA, NEW YORK, ASSIGNOR T GENERAL ELECTRIC COMPANY, A CORPORATION 0F NEW YORK I GAS TIGHT SEAL Application mea 'september s, 192s. seria No. 304,141.

of which it is attached to the rectier casing i My invention relates to gas tight insulating seals and has for its principal object the provision of an improved anode seal for mercury arc rectifier's.

In the operation of mercury arc rectifiers considerable diiiiculty `is encountered in maintaining a gas tight joint or seal between the anode leads, the metallic casing and the interposed insulation. The repeated temperature changes between operating and shut down conditions, as well as variations during operation tend to cause unequal expansion and contraction of themetal and insulating parts of the seal whereby leaks often develop between them. In accordance with my invention this diiculty is substantially eliminated by a novel construction of v the seal.

ln accordance with my invention an insulating compound placed between the anode stem and ai, surrounding shell is compressed and forced into intimate contact with the surfaces of the stem and shell by the insertion of a metallic cylinder, this metallic cylinderbeing constricted, and welded to the anode stem at theexposed end in such a way that the leakage path along the anode stem is greatly increased.

rl`he novel features which l consider characteristic of my invention are pointed outl in the appended claims. The invention itself however, will best be understood b y referp ence to the accompanying drawing 1n which the single gure illustrates an anode for.a mercury are rectifier with the seal, made`in accordance with my invention, shown in cross section.

Referring to the drawing in detail, 1 illustrates in cross section a part ofthe mercuryl arc rectifier casing. Part 2 is the anode supported on stud 3 which is in` turn supporte byV anode stem 4. The stem 4 is surrounded by insulating material 5 Iwhich is preferably anv insulating compound composed of mica and a vitreous binder such as glass. This vcompound is known as micalex and is fullydescribed in Letters Patent of Percy Broad# bent Crossley, Reissue 15,727.l The insulation 5 and stem 4 are placed inside of shell 6 which isp'revided with a ange 7 by means .has any ,imbedded in the insulation between Il and part of its length convenient diameter such that it is 6 and has a. thickness such that it forces the insulation 5 into intimate contact with the surfaces of Lland 6 which may have corrugsft e l material further, throughout its entire body,-

tions or grooves therein Aandcompresses to a uniform predetermined density. The cylinder 8 is constricted for a considerable so that it fits snugly against stem 4 and is welded to this stem at its ex posed end. In this manner a gas tight pock-a et is formed between 4 and 8 so that if a leak starts along the surface of 4 it must travel along both surfaces of the cylinder 8 before reaching the atmosphere. The length of the constricted part of the cylinder 8, in relation to the total length of the cylinder, may be varied to obtain the required com ression of the insulation 5.

The rshellv 6 being exposed to the surround; ing air undergoes much less temperature change than the anode stem. There is theren fore, less likelihood of leaks developing along its surface than there is of such leaks develop-ing along theanode stem and less precau tions need thereforebe taken. The cylinder d mate' contact with the ridges on the inner surface of shell 6 toA prevent leakage.

In order that stem 4 may be kept as cool as possible, cooling Huid is caused to circulate within it. For this purpose it is provided with a recess v9., A reservoir l0 is fastened over this recess by means of flange l1, so that an opening'in the bottom of the reservoir 10 registers with the recess 9. Apipe 12, haring an outside diameter smaller than the v lower end is near the bottom of the recess terial surrounding said stem and shell, and a ing arranged to force said rial into intimate contact with said core and 'and its upper end is within reservoir 10.

Reservoir 10 is lled with cooling fluid, which is preferably Water, so that the evel is above the upper end of pipe 12. In operation automatic circulation of the fluid takes place, down along the walls of the recess and up through the. pipe 12.

- What I claim as new and desire to secure by Letters Patentof the United States, is:

1. A.' gas tight seal including a core of conductive material, a layer of insulating macore, a metallic shell surrounding said insulating material, and a cylindrical member embedded in said insulating material and pressing said insulating material into intimate Contact with said core and said shell, said member being attached at its exposed end to said core.-

2. An anode seal for mercury are rectiers including an anode stem, a shell surrounding said stem, insulation interposed between said member surrounding said stem and embedded at one of its ends in said insulation, said end of said member being arranged to force said insulation into intimate contact with said stem and said shell, said member being constricted at its y,exposed end and welded to said anode stem.l

3. A` gas tight seal including a core of conductive material, a layer of insulating material surrounding said core, a metallic shell surrounding said insulating material, and a I cylindrical member embedded at one of its ends in said insulating material, said end be'- said shell, said member being attached at its exposed end to said core, the opposed surfaces of said shell and cylindrical member being provided with proiections which extend into said insulation.

In a mercury arc device', an evacuated casing, an electrode stem, a shell surrounding said v,stem `and connected te said casing, a,

body of insulating material composed of mica and a vitreous binder interposed between said stem and said shell, and means including a cylindrical member. adapted to be pressed into said material-and between said insulating mate' surrounding said stem and embedded at one of its ends in said insulation, said end of said member being arranged to compress said insulation to a predetermined density and into gas tight Contact with said-stem and shell, said member being connected at its eX- posed end in stem.

In witness whereof, l' have hereunto set my hand this 4th day of September, 1928.

GUENTHEB; BUECHNER.

gas tight relation to said anode stem and shell while said material is in plastic condition to force said material into intimate contact with saidstem and shell, where- 'g by leakage between said stem and shell into said casing when said material is in solid condition is prevented. 4 e

5. A gas tight seal including a coreo conductive material, a layer of insulating material surrounding said core, a metallic shell surrounding said insulating material, and a cylindrical member embedded in said insulating material and arranged to compress said insulating material to a uniform prede- Pr l- 

